A controller for a vehicle is known which performs only a lane deviation alarm function based on an image picked-up by a CCD camera when an information not-obtainable state in a magnetic nail sensor occurs under a situation where the lane deviation alarm function for informing that a host vehicle is deviated from a traveling lane and a steering control function for preventing or suppressing the deviation are performed based on the magnitude of magnetism detected by the a magnetic nail sensor.
[Patent Document 1] Japanese Laid-open Patent Publication No. 2001-273597